Valve drive device

ABSTRACT

A valve drive device comprising a valve body drive mechanism including a drive gear, a driven gear for turning the valve body, and a power transmission switching part provided with a protruded part of the drive gear and a turning restriction part turnably attached to the driven gear. The turning restriction part includes a lever part which is provided with a first contact part structured to contact with the protruded part when the drive gear is turned to a first direction and a second contact part structured to contact with the protruded part when the drive gear is turned to an opposite direction to perform a separating operation from a contact position with a lever turning restriction part. The second contact part is formed in a shape having an interference avoiding part on a side of the first contact part.

CROSS REFERENCE TO RELATED APPLICATION

The present invention claims priority under 35 U.S.C. § 119 to JapaneseApplication No. 2018-226691 filed Dec. 3, 2018, and the entire contentof which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a valve drive device structured todrive a valve for adjusting a flow rate of a fluid.

BACKGROUND

Conventionally, in order to cool an inside of a chamber of arefrigerator or the like, a refrigerant valve device structured tosupply refrigerant has been known. One of the refrigerant valve devicesincludes a valve drive device structured to drive a valve and adjust asupply amount of refrigerant which is supplied to an inside of a chamber(Japanese Patent No. 5615993 (Patent Literature 1)).

The refrigerant valve device described in Patent Literature 1 includes avalve body which is turnable with a position shifted to an opening ofeither of a refrigerant inlet and a refrigerant outlet as a center in abase provided with the refrigerant inlet, the refrigerant outlet and avalve seat face, and a valve body drive mechanism structured to turn thevalve body. The valve body drive mechanism includes a stepping motor(hereinafter, referred to as a motor), a pinion which is integrallyrotated with a drive shaft of the motor, and an output gear which isengaged with the pinion and is integrally turned with the valve body.

When the motor is rotated, the output gear, i.e., the valve body is alsoturned through the pinion which is integrally rotated with the motor. Asa result, the valve body is capable of adjusting an opening degree of anopening of either of the refrigerant inlet and the refrigerant outlet toadjust a supply amount of the refrigerant.

In the valve body drive mechanism, when the pinion is rotated in aforward rotation direction, the output gear and the valve body can beturned from a first turning restricted position to a second turningrestricted position which is a position obtained by rotating the motorin the forward rotation direction.

In order to adjust a supply amount of the refrigerant, when the motor isrotated in a reverse rotation direction from the second turningrestricted position to the first turning restricted position, an armpart of the output gear and an abutted part of the pinion are abuttedwith each other and a state that a further turning of the pinion in thereverse rotation direction is restricted is obtained. Therefore, sincethe motor tries to continue to rotate to the reverse rotation directionin a state that rotation of the pinion to the reverse rotation directionis restricted, the motor occurs step-out. As a result, when the step-outof the motor is occurred, the arm part and the abutted part are collidedwith each other and a noise (collision noise) may be generated.

SUMMARY

In view of the problem described above, the present invention provides avalve drive device including a valve body drive mechanism structured todrive a valve body, the valve drive device being capable of reducingnoise when the valve body is driven and of smoothly performing powerswitching and, in addition, when a fluid is flowed through an inside ofthe valve drive device, a possibility that a foreign matter enters intoa portion performing power transmission switching of the valve bodydrive mechanism to cause an operation failure is reduced.

To solve the above problem, the present invention provides a valve drivedevice including a valve body drive mechanism structured to drive avalve body. The valve body drive mechanism includes a drive gearstructured to be rotatably driven by a motor, a driven gear structuredto turn the valve body through rotation of the drive gear in a statethat the driven gear is engaged with the drive gear, and a powertransmission switching part which is capable of switching between apower transmission state that the drive gear is engaged with the drivengear to transmit power of the motor to the driven gear and a powernon-transmission state that an engaging state of the drive gear with thedriven gear is released. The power transmission switching part includesat least one protruded part which is formed in the drive gear and isprotruded in a radial direction of the drive gear, and a turningrestriction part which is turnably attached to the driven gear and isengageable with the protruded part. The turning restriction part isprovided with a turning shaft which is inserted into the driven gear,and a lever part which is extended from the turning shaft in acircumferential direction of the driven gear and is urged with an urgingforce toward an outer side in a radial direction of the driven gear. Thedriven gear is provided with a lever turning restriction part structuredto contact with the lever part to restrict turning of the turningrestriction part to the outer side in the radial direction of the drivengear. The lever part is structured to perform a contact operation withthe protruded part being turned and a separating operation from acontact position with the lever turning restriction part against theurging force, and the lever part is provided with a first contact partstructured to contact with the protruded part when the drive gear isturned to a first direction, and a second contact part structured tocontact with the protruded part when the drive gear is turned to asecond direction which is an opposite direction to the first direction.When the protruded part is turned to the first direction and iscontacted with the first contact part, the lever part is pressed by theprotruded part to turn the driven gear, and a tooth of the drive gearand a tooth of the driven gear are engaged with each other and therebythe power transmission state is obtained and, when the protruded part isturned to the second direction and is contacted with the second contactpart, the lever part is turned to an inner side in the radial directionagainst the urging force and a tooth of the drive gear is not engagedwith a tooth of the driven gear to idle the drive gear and thereby thepower non-transmission state is obtained. In addition, in a case that alocus of a circle formed by a tip end in the radial direction of theprotruded part when the drive gear is turned is defined as a firstcircle locus, and that a locus of a circle formed by a tip end of thefirst contact part in the radial direction of the driven gear when theprotruded part is turned to the first direction and is contacted withthe first contact part is defined as a second circle locus, the secondcontact part is formed in a shape having an interference avoiding parton a side of the first contact part in an interference region surroundedby a first circle formed by the first circle locus and a second circleformed by the second circle locus.

In this case, the above-mentioned “interference avoiding part” describedas that “the second contact part is formed in a shape having aninterference avoiding part on a side of the first contact part in theinterference region . . . ” means that a retreating shape is formed forthe protruded part in the second contact part of the lever part which isto be contacted with the protruded part and, in the portion of theretreating shape, the protruded part does not contact with the leverpart. In other words, in the interference region, a portion on the firstcontact part side of the second contact part is formed in a shape so asto have a gap space in which the second contact part does not contactwith the protruded part.

According to this embodiment, a state of power transmission can beswitched by switching an engaging state of the drive gear with thedriven gear in the power transmission switching part and, since themotor is not required to step out, noise can be reduced.

While advancing improvement of the power transmission switching partcapable of reducing noise, the present inventor has recognized thatthere is a case which is required to consider that the valve drivedevice is installed in a fluid path through which a fluid includingforeign matters such as copper powder is flowed through an inside of thevalve drive device. In this case, the present inventor has found that,as operations of the power transmission part, when an operation that thelever part contacts with the protruded part and an operation that thelever part is turned against the urging force and is separated from thecontact position with the lever turning restriction part are repeated,the foreign matter may enter into a region formed between the lever partand the lever turning restriction part. Further, the present inventorhas recognized that, when the foreign matters enter into the region andare accumulated, the lever part becomes unable to be returned to theoriginal contact position and the power transmission part may occur anoperation failure.

In order to solve this new problem, in the present invention, the secondcontact part is structured in a shape having an interference avoidingpart on a side of the first contact part in an interference regionsurrounded by a first circle formed by the first circle locus and asecond circle formed by the second circle locus.

According to this embodiment, the second contact part is formed in ashape having the interference avoiding part and thus, a timing when theprotruded part is abutted with the second contact part of the lever partby turning of the drive gear becomes later than that in a shape havingno interference avoiding part. As a result, a time period in a“separated” state in the contacting and separating operation of thelever part becomes smaller than that in the shape having no interferenceavoiding part. In the “contacting” state in the contacting andseparating operation, a foreign matter is structurally unable to enterinto the region and thus, when a time period of the “separated” state isshortened, a foreign matter is hard to enter into the region by theshortened time period.

Therefore, even in a case that the valve drive device is installed in afluid path including foreign matters such as copper powder, the foreignmatter can be restrained from entering into the region and thus, apossibility can be reduced that the lever part becomes unable to returnto the original contact position. As a result, a possibility that thepower transmission switching part occurs an operation failure due to aforeign matter can be reduced.

Further, in the present invention, it is preferable that, in the valvedrive device, a continuous portion continuing from a portioncorresponding to the interference avoiding part of the second contactpart to the first contact part is formed to be a curved surface on whichthe protruded part is capable of sliding.

When the protruded part is turned by turning of the drive gear to face aportion corresponding to the interference avoiding part of the secondcontact part, the protruded part is initially in a non-contact statewith the second contact part. After that, when the protruded part ismoved toward the first contact part side, the non-contact state isswitched to a contact state with the second contact part. When switchedto the contact state, the protruded part begins to push the secondcontact part. Then, the lever part is pushed by the turning protrudedpart and is turned against the urging force with the turning shaft as asupport point and the lever part is separated from the contact positionwith the lever turning restriction part.

In this case, in this embodiment, the continuous portion continuing froma portion corresponding to the interference avoiding part to the firstcontact part is formed to be a curved surface on which the protrudedpart is capable of sliding and thus, the lever part is smoothly turnedand its turning operation is stable.

Further, in the present invention, it is preferable that, in the valvedrive device, the interference avoiding part is structured of a recessedpart between the contact position of the lever part with the leverturning restriction part and the first contact part.

A portion of the second contact part of the lever part which iscontacted with the lever turning restriction part does not originallycontact with the protruded part. The recessed part is provided betweenthe contact position of the lever part with the lever turningrestriction part and the first contact part, and the interferenceavoiding part is structured of the recessed part and thus, in a statethat the contact state and the contact position of the lever part withthe lever turning restriction part are stabilized, a delay of the timingcan be easily realized by the recessed part.

Further, in the present invention, it is preferable that, in the valvedrive device, when the protruded part pushes the second contact part ofthe lever part while the drive gear is turned in the second direction,the lever part is turned with the turning shaft as a turning supportpoint, and a turning angle of the lever part when the protruded part isseparated from the second contact part is a maximum value.

According to this embodiment, it is structured that a turning angle ofthe lever part becomes a maximum value when the protruded part isseparated from the second contact part and thus, the lever part is notrequired to be turned unnecessarily. As a result, the structure can besimplified.

Further, in the present invention, it is preferable that, in the valvedrive device, the motor is a stepping motor, and the protruded part isseparated from the second contact part in a step next to a stepcorresponding the maximum value of the turning angle of the lever part.

In this embodiment, the protruded part is separated from the secondcontact part in a step next to the step corresponding to the maximumvalue of the turning angle of the lever part. As a result, design andoperation control can be simplified.

Further, in the present invention, it is preferable that, in the valvedrive device, in a state that the lever turning restriction partrestricts turning of the turning restriction part, the lever turningrestriction part is formed with a gap space between the lever turningrestriction part and the turning shaft.

In this embodiment, in a state that the lever turning restriction partrestricts turning of the turning restriction part, the lever turningrestriction part is formed with a gap space between the lever turningrestriction part and the turning shaft and thus, the lever turningrestriction part and the turning shaft are capable of avoiding directlycontacting with each other. As a result, positioning of the turningrestriction part is not required to perform by a portion of the turningshaft, and the lever turning restriction part performs positioning bycontacting with a portion other than the turning shaft of the turningrestriction part and thus, influence of variation of dimension or thelike of the turning shaft can be reduced and positional accuracy of thetip end of the lever part in a state that the turning restriction partdoes not contact with the protruded part can be stabilized.

Further, in the present invention, it is preferable that, in the valvedrive device, the second contact part of the lever part is located on anouter peripheral side in the radial direction of the driven gear and isformed to be a curved surface which is extended along a circumferentialdirection of the driven gear.

In this embodiment, the second contact part of the lever part is locatedon an outer peripheral side in the radial direction of the driven gearand is formed to be a curved surface which is extended along acircumferential direction of the driven gear. Therefore, the secondcontact part is contacted with the protruded part and is turned to aninner side in the radial direction of the driven gear and, when theprotruded part is separated from the second contact part, in comparisonwith a case that the second contact part is formed in a straight shape,the curved surface of the second contact part can be located at a closerposition to the protruded part to be contacted next. In other words, thesecond contact part contacted with the protruded part is separated fromthe protruded part at a position which is close to the positionrestricted by the lever turning restriction part. Therefore, incomparison with a case that the second contact part is formed in astraight shape, when the protruded part is separated from the secondcontact part, a force generated when the second contact part and thelever turning restriction part are contacted with each other can be madeweak. As a result, generation of noise at a time when the second contactpart and the lever turning restriction part are contacted with eachother in turning operation of the turning restriction part can berestrained.

Further, in the present invention, it is preferable that, in the valvedrive device, the driven gear is formed with a protruded shape partwhich is protruded to an outer side in the radial direction and isprotruded from a face on one side of the driven gear in an axialdirection of the driven gear, and an inner side in the protruded shapepart in the radial direction of the driven gear is formed with the leverturning restriction part.

In this embodiment, the above-mentioned operations and effects can beobtained in the region based on the structure in which the lever turningrestriction part is formed on an inner side in the radial direction ofthe protruded shape part provided in the driven gear.

Further, in the present invention, it is preferable that, in the valvedrive device, when the protruded part contacts with the second contactpart and the lever part is turned to an inner side in the radialdirection against the urging force, the driven gear is provided with aco-turning prevention part which restricts that, when the second contactpart is pushed by the protruded part in a turning direction of theprotruded part, the driven gear is turned in a direction correspondingto a turning direction of the drive gear.

In this embodiment, an accompanying turning of the driven gear by thedrive gear can be restricted by the co-turning prevention part and thus,an idling state of the drive gear is maintained and the powernon-transmission state can be maintained surely.

Further, in the present invention, it is preferable that, in the valvedrive device, the turning restriction part is provided with a foot partprovided on an opposite side to the lever part of the turning shaft inan axial direction of the turning shaft, and the foot part restricts aninclination of the turning shaft by the urging force which urges thelever part.

In this embodiment, the turning restriction part is provided with a footpart provided on an opposite side to the lever part of the turning shaftin an axial direction of the turning shaft, and the foot part restrictsan inclination of the turning shaft by the urging force which urges thelever part and thus, an inclination of the turning shaft can berestrained. Therefore, power transmission switching in the powertransmission switching part can be performed smoothly.

Further, in the present invention, it is preferable that, in the valvedrive device, the foot part is extended to an opposite direction to adirection that the lever part is urged.

In this embodiment, the phrase that “the foot part is extended to anopposite direction to a direction that the lever part is urged”includes, in addition to the direction reversed by 180 degrees withrespect to the urging direction, a direction extended in a directionwhose vector component of force is applied to an opposite direction tothe urging direction.

In this embodiment, the lever part is urged by an urging force.Therefore, a turning moment which inclines the turning shaft withrespect to an axial direction is generated in the turning shaft by theurging force. The foot part in this embodiment is extended to anopposite direction to a direction where the lever part is urged andthus, when the turning shaft is going to be inclined by the turningmoment, the foot part is pressed against the driven gear and aninclination of the turning shaft can be restricted surely.

Further, in the present invention, it is preferable that, in the valvedrive device, the foot part is extended from the turning shaft toward aninner side in the radial direction of the driven gear.

In this embodiment, in order to structure that the lever part is capableof engaging with the protruded part of the drive gear, the turningrestriction part is required to be provided in the driven gear at aposition close to an outer peripheral side in the radial direction ofthe driven gear. Therefore, when the foot part is structured so as toextend from the turning shaft toward an outer side in the radialdirection of the driven gear, a length of the foot part becomes short.

According to this embodiment, the foot part is extended from the turningshaft toward an inner side in the radial direction of the driven gearand thus, in comparison with a case that the foot part is extended to anouter side in the radial direction, a length of the foot part can bemade long. As a result, the turning shaft can be hard to be inclined.

Effects of the Invention

According to the present invention, in a valve drive device including avalve body drive mechanism structured to drive a valve body, the valvedrive device is capable of reducing noise when the valve body is drivenand of smoothly performing power switching and, in addition, when afluid is flowed through an inside of the valve drive device, apossibility that a foreign matter enters into a portion of the valvebody drive mechanism performing power transmission switching to cause anoperation failure can be reduced.

Other features and advantages of the invention will be apparent from thefollowing detailed description, taken in conjunction with theaccompanying drawings that illustrate, by way of example, variousfeatures of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, withreference to the accompanying drawings which are meant to be exemplary,not limiting, and wherein like elements are numbered alike in severalFigures, in which:

FIG. 1 is a perspective view showing a valve drive device in accordancewith an embodiment of the present invention.

FIG. 2 is a side cross-sectional view showing a valve drive device inaccordance with an embodiment of the present invention.

FIG. 3 is a perspective view showing a valve body drive mechanism in thevalve drive device.

FIG. 4 is a perspective view showing a valve body drive mechanism in thevalve drive device.

FIG. 5 is a perspective view showing an output side gear in the valvebody drive mechanism.

FIG. 6 is a plan view showing the output side gear.

FIG. 7 is an exploded perspective view showing a driven portion in thevalve body drive mechanism.

FIG. 8 is a perspective view showing a driven gear in the valve bodydrive mechanism which is viewed from an upper face side.

FIG. 9 is a perspective view showing the driven gear which is viewedfrom an upper face side and in a different direction from that in FIG.8.

FIG. 10 is a perspective view showing the driven gear which is viewedfrom a bottom face side.

FIG. 11 is a perspective view showing a turning restriction part in thevalve body drive mechanism.

FIG. 12 is a perspective view showing a relationship between a foot partof the turning restriction part and a foot part accommodation part ofthe driven gear.

FIG. 13A is a perspective view showing a valve body viewed from anopposite side to a valve seat face, and FIG. 13B is a perspective viewshowing the valve body viewed from the valve seat face side.

FIG. 14 is a view showing an opening/closing state of the valve bodydrive mechanism in respective steps.

FIG. 15 is a view showing phase states between the output side gear andthe driven gear and states of the valve body.

FIG. 16 is a view showing phase states between the output side gear andthe driven gear and states of the valve body.

FIG. 17 is a view showing a phase state between the output side gear andthe driven gear and a state of the valve body.

FIG. 18 is a view showing states of the valve body drive mechanism in anorigin return operation.

FIG. 19 is a view showing states of the valve body drive mechanism inthe origin return operation.

FIG. 20 is a view showing states of the valve body drive mechanism whenthe valve body is driven.

FIG. 21 is a view showing states of the valve body drive mechanism whenthe valve body is driven.

FIG. 22 is a view showing a relationship between the output side gearand the driven gear at an origin position.

FIGS. 23A and 23B are views showing states that an accompanying turningof the driven gear with the drive gear is restricted by a second turningrestriction part.

FIG. 24 is a view showing a relationship of a center position of aturning shaft of the turning restriction part with respect to the drivengear.

FIG. 25 is an explanatory schematic view showing a relationship betweenan urging force applied to the turning restriction part and a foot part.

FIGS. 26A and 26B are schematic views for explaining an effect when asecond contact part of a lever part in the turning restriction part isstructured to be a curved surface.

FIG. 27 is a perspective view showing a valve body drive mechanismprovided with a foreign matter entry restraining part which is viewedfrom an upper side.

FIG. 28 is a perspective view showing the valve body drive mechanismshown in FIG. 27 in which a part of the valve body drive mechanism isomitted.

FIG. 29 is a perspective view showing the valve body drive mechanismshown in FIG. 27 in which a part of the valve body drive mechanism isomitted and which is viewed from an upper side.

FIG. 30 is a perspective view showing a turning restriction partprovided with a foreign matter entry restraining part.

FIGS. 31A and 31B are plan views for explaining an operation of theturning restriction part provided with the foreign matter entryrestraining part. FIG. 31A shows a state before turning of a lever partis started and FIG. 31B shows a state that the lever part has beenturned.

FIG. 32 is a perspective view showing a valve body drive mechanismprovided with a foreign matter entry restraining part whose structure isdifferent from that in FIG. 27 and which is viewed from an upper side.

FIGS. 33A and 33B are plan views showing a main part of a valve bodydrive mechanism provided with an interference avoiding part which areviewed from an upper side.

FIG. 33A shows a state before turning of a lever part is started andFIG. 33B shows a state that the lever part has been turned.

FIG. 34 is an explanatory view showing a relationship between a turningposition of a drive gear and a turned position of a lever part.

FIG. 35 is a graph showing a relationship between a turning position ofa drive gear and a turned position of a lever part.

DETAILED DESCRIPTION

Embodiments of the present invention will be described below withreference to the accompanying drawings. In respective embodiments, thesame reference signs are used in the same structures and the structuresare described only in a first embodiment and their descriptions in thefollowing embodiments are omitted.

In the following descriptions, in order to easily understand thestructure, a specific structure of a foreign matter entry restrainingpart and an interference avoiding part will be described later and,first, a general structure of a valve drive device is described which iscapable of reducing noise when a valve body is driven and of performingsmooth power transmission switching.

Then, after the description of the general structure of a valve drivedevice, a specific structure of a foreign matter entry restraining partwill be described in detail below which is provided for reducing apossibility that, when a fluid is flowed in an inside of the valve drivedevice, a foreign matter enters to a portion where power transmissionswitching of the valve body drive mechanism is performed to cause anoperation failure.

Next, a specific structure and the like of an interference avoiding partwill be described in detail below.

Embodiments [Summary of Valve Drive Device]

A valve drive device 10 in accordance with an embodiment of the presentinvention will be described below with reference to FIGS. 1 through 4.The valve drive device 10 is, as an example, mounted on a refrigeratorto adjust a supply amount of refrigerant (fluid) for cooling an insideof a chamber. The valve drive device 10 includes a valve main body 12,an inflow pipe 14 extended from the valve main body 12, a first outflowpipe 16 and a second outflow pipe 18 extended in parallel to the inflowpipe 14, and a cover member 20 which covers an upper part of the valvemain body 12. In the following descriptions, for convenience, anextended direction of the inflow pipe 14, the first outflow pipe 16 andthe second outflow pipe 18 is defined as an upper and lower direction,and it is defined that the valve main body 12 is located on an upperside, and the inflow pipe 14, the first outflow pipe 16 and the secondoutflow pipe 18 are located on a lower side.

In FIG. 2, the valve main body 12 includes a base member 22, a motor 24,a seal cover 26, a base main body 28, and a valve body drive mechanism30. The base main body 28 has an upper face 28 a. The base main body 28is attached with the inflow pipe 14, the first outflow pipe 16 and thesecond outflow pipe 18 respectively. The seal cover 26 is attached to anupper part of the base main body 28. The base main body 28 and the sealcover 26 structure a valve chamber 32.

As shown in FIG. 3, the upper face 28 a is formed with a fluid inlet 28b. The fluid inlet 28 b is communicated with the inflow pipe 14 which isattached to the base main body 28. Refrigerant (fluid) is supplied intothe valve chamber 32 through the inflow pipe 14.

The base main body 28 is attached with a valve seat constituting member34 (FIGS. 2, 3 and 7, and FIGS. 15 through 17). The first outflow pipe16 and the second outflow pipe 18 are respectively attached to the valveseat constituting member 34, and the valve seat constituting member 34is provided with a first fluid outlet 34 a communicated with the firstoutflow pipe 16 and a second fluid outlet 34 b communicated with thesecond outflow pipe 18. A fluid supplied into the valve chamber 32through the inflow pipe 14 is flowed out to the first outflow pipe 16through the first fluid outlet 34 a, or flowed out to the second outflowpipe 18 through the second fluid outlet 34 b.

As shown in FIG. 2, the motor 24 includes a stator 36 and a rotor 40 towhich a drive magnet 38 is attached. The stator 36 is disposed so as tosurround a periphery of the rotor 40 with the seal cover 26 interposedtherebetween.

In this embodiment, the stator 36 includes core members 42 as shown inFIG. 2. A winding is wound around the core member 42 of the stator 36 asa drive coil 37. One end of the drive coil 37 (winding) wound in thestator 36 is bound and connected with one end of a motor terminal notshown. Motor terminals not shown are electrically connected with aconnector, a circuit board or the like not shown to supply power to thestator 36.

As shown in FIGS. 2 and 3, the rotor 40 includes the drive magnet 38, adrive gear 46 and a support shaft 48. The drive gear 46 and the drivemagnet 38 are rotatably attached to the support shaft 48. The drivemagnet 38 is attached to the drive gear 46. An upper end of the supportshaft 48 is supported by a bearing part 26 a formed in the seal cover26, and a lower end of the support shaft 48 is supported by a bearingpart 28 c formed in the base main body 28. In this embodiment, when thestator 36 (drive coil 37) is excited, the rotor 40 is rotated in aninside of the valve chamber 32 by the drive magnet 38 with the supportshaft 48 as a rotating center.

[Summary of Valve Body Drive Mechanism]

A structure of a valve body drive mechanism 30 will be described belowwith reference to FIGS. 3 through 12. As shown in FIGS. 3 and 4, thevalve body drive mechanism 30 includes the motor 24, the drive gear 46,a driven gear 50 and a power transmission switching part 52. The powertransmission switching part 52 is, as described below, structured sothat power transmission between the drive gear 46 and the driven gear 50can be switched to a power transmission state that power is transmittedand a power non-transmission state that the power is not transmitted. Inthis embodiment, the power transmission switching part 52 includes aprotruded part 46 b of the drive gear 46 and a turning restriction part62 described below.

As shown in FIGS. 5 and 6, the drive gear 46 is formed with a gear part46 a on a lower end part. A plurality of the protruded parts 46 b isformed on an upper side with respect to the gear part 46 a. A tooth ofthe gear part 46 a corresponding to the protruded part 46 b in acircumferential direction of the drive gear 46 is structured as a lockavoiding tooth 46 c.

A plurality of the protruded parts 46 b is protruded from a main body 46d of the drive gear 46 to an outer side in a radial direction of thedrive gear 46. In this embodiment, the protruded part 46 b is, as anexample, formed in a flat plate shape. In this case, a shape of theprotruded part 46 b is not limited to a flat plate shape and may beformed in a shape which is engageable with a turning restriction part 62described below. In this embodiment, a plurality of the protruded parts46 b is respectively formed at positions corresponding to an “N”-pole oran “S”-pole of the drive magnet 38 in the circumferential direction ofthe drive gear 46.

In this embodiment, the number of magnetic poles of the drive magnet 38is, as an example, 8 (eight) poles. Therefore, in this embodiment, theprotruded part 46 b is provided at four positions in the drive gear 46.Specifically, the protruded part 46 b is provided in the drive gear 46at equal intervals in the circumferential direction of the drive gear 46and, in this embodiment, the protruded parts 46 b are formed at fourpositions and thus, the protruded parts 46 b are provided at every 90degrees (see FIGS. 18 through 21). In this embodiment, the protrudedpart 46 b is formed in a thickness corresponding to a tooth thickness ofa tooth of the gear part 46 a of the drive gear 46.

As shown in FIG. 6, in this embodiment, a tooth-tip circle diameter ofthe lock avoiding teeth 46 c is set to “d1”. On the other hand, in thegear part 46 a, a tooth-tip circle diameter of teeth other than the lockavoiding teeth 46 c is set to “d2”. In this embodiment, the tooth-tipcircle diameter “d1” is set to be smaller than the tooth-tip circlediameter “d2”. In FIG. 6, the circle shown by the alternate long andshort dash line indicates the tooth-tip circle diameter of the lockavoiding teeth 46 c, and the circle shown by the two-dot chain lineindicates the tooth-tip circle diameter of the teeth other than the lockavoiding teeth 46 c.

Next, a structure of a driven gear 50 which is driven by the drive gear46 will be described below. As shown in FIG. 2, a support shaft 54 isinserted into a center in a radial direction of the driven gear 50. Thedriven gear 50 is structured so as to be turnable with respect to thesupport shaft 54. A valve body 56 is provided on a lower side of thedriven gear 50. In this embodiment, the valve body 56 is integrallystructured with the driven gear 50 so as to be turnable with respect tothe support shaft 54. The valve seat constituting member 34 is providedon a lower side with respect to the valve body 56. An upper face of thevalve seat constituting member 34 is structured as a valve seat face 34c.

A through-hole 34 d is provided at a center of the valve seatconstituting member 34, and the support shaft 54 is inserted into thethrough-hole 34 d. The support shaft 54 is not shown in FIG. 4. In FIG.4, the arrow with the reference sign “R1” indicates a first directionwhich is one rotational direction of the drive gear 46, and the arrowwith the reference sign “R2” indicates a second direction which is theother rotational direction of the drive gear 46.

A holding member 58 is attached to an upper part of the driven gear 50.The support shaft 54 is inserted into the holding member 58. Further,the holding member 58 is structured to be a cylindrical tube-shapedmember which is formed with a flange part 58 a in its upper part, and atube-shaped part 58 b is inserted into a torsion spring 60 as an “urgingmember” and the torsion spring 60 is held by the holding member 58.Further, the turning restriction part 62 in a lever shape is attached toan upper part of the driven gear 50.

[Driven Gear]

As shown in FIGS. 4 and 7 through 10, the driven gear 50 is formed onits outer peripheral portion with a meshing part 50 a where a pluralityof teeth are successively formed along a circumferential direction and anon-meshing part 50 b where a tooth is not formed. Further, in the outerperipheral portion of the driven gear 50, a first turning restrictionpart 50 c structured to restrict turning to the first direction “R1”side of the driven gear 50 is provided at an end part on the seconddirection “R2” side of the meshing part 50 a, and a non-meshing part 50b is provided at an end part on the first direction “R1” side of themeshing part 50 a.

In addition, an end part on the first direction “R1” side of thenon-meshing part 50 b is provided with a second turning restriction part50 k as a “co-turning prevention part”. In FIGS. 8 and 9, the arrow withthe reference sign “R1” indicates a driven turning direction of thedriven gear 50 when the drive gear 46 is rotated in the first direction,and the arrow with the reference sign “R2” indicates a driven turningdirection of the driven gear 50 when the drive gear 46 is rotated in thesecond direction. In FIGS. 18 through 21, the reference sign of thesecond turning restriction part 50 k is omitted.

In this embodiment, as mainly shown in the step S0 in FIG. 15, when areference circle diameter of the drive gear 46 is compared with areference circle diameter of the driven gear 50, the reference circlediameter of the driven gear 50 is formed to be larger. In addition, thenumber of the teeth of the gear part 46 a of the drive gear 46 is set tobe smaller than the number of the teeth formed in the meshing part 50 aof the driven gear 50. Therefore, in a power transmission state that thegear part 46 a of the drive gear 46 and the meshing part 50 a of thedriven gear 50 are engaged with each other and turned together, rotationof the motor 24 can be transmitted to the driven gear 50 in adecelerated state and thus, a large torque can be obtained even when asmall power source is used and a valve body 56 described below can bedriven surely.

Further, as shown in FIGS. 7 through 10, a center part of the drivengear 50 is provided with a through-hole 50 d into which the supportshaft 54 is inserted. In addition, a recessed part 50 e which receives apart of the holding member 58 and is engaged with the holding member 58is formed around the through-hole 50 d in an upper face 50 p of thedriven gear 50. The holding member 58 engaged with the recessed part 50e structures a shaft part of the driven gear 50 together with thesupport shaft 54 and holds the torsion spring 60.

In addition, a holding part 50 f in a circular arc shape is provided onthe upper face 50 p of the driven gear 50 so as to surround the recessedpart 50 e. As shown in FIG. 4, the holding part 50 f is structured so asto engage with one end 60 a of the torsion spring 60 and hold the oneend 60 a. Further, the upper face 50 p of the driven gear 50 is providedwith a through-hole 50 g as a “hole part”, a lever turning restrictionpart 50 h and a slit part 50 q. The slit part 50 q is communicated withthe through-hole 50 g and is, as an example, extended from thethrough-hole 50 g toward an inner side in the radial direction of thedriven gear 50. In this embodiment, the slit part 50 q is set in a sizeso that a foot part 62 h of the turning restriction part 62 describedbelow can be inserted.

In FIG. 10, an under face 50 r of the driven gear 50 is formed with afoot part accommodation part 50 s. The foot part accommodation part 50 sis communicated with the through-hole 50 g and the slit part 50 q in theunder face 50 r. The foot part accommodation part 50 s is formed so asto permit turning of the foot part 62 h when the foot part 62 h of theturning restriction part 62 passed through the slit part 50 q is turnedwith the turning shaft 62 a as a support point. In this embodiment, thefoot part accommodation part 50 s is formed in the under face 50 r as afan-shaped recessed part extended to an inner side in the radialdirection of the driven gear 50 with the through-hole 50 g as a center.In this embodiment, the under face 50 r is provided with the foot partaccommodation part 50 s in a recessed shape and thus, the foot part 62 hcan be prevented from protruding from the under face 50 r and the sizeof the valve body drive mechanism 30 can be reduced.

In FIGS. 8, 9 and 24, the driven gear 50 is formed with a protrudedshape part 50 n which is protruded to an upper side from the upper face50 p and is protruded toward an outer side in the radial direction. Thefirst turning restriction part 50 c is formed on one side of theprotruded shape part 50 n in the circumferential direction of the drivengear 50, and the second turning restriction part 50 k is formed on theother side of the protruded shape part 50 n. The lever turningrestriction part 50 h is formed in the protruded shape part 50 n on aninner side in the radial direction of the driven gear 50. The leverturning restriction part 50 h of the protruded shape part 50 n is formedin a recessed shape toward an outer side in the radial direction so asto receive a part of the turning shaft 62 a and a part of the lever part62 b of the lever-shaped turning restriction part 62.

At least a part of the through-hole 50 g is provided in a recessedportion of the protruded shape part 50 n which is recessed toward anouter side in the radial direction. In FIG. 24, the circle indicated bythe two-dot chain line with the reference sign 50 m is a tooth-bottomcircle of the teeth of the meshing part 50 a of the driven gear 50. Inthis embodiment, a part of the through-hole 50 g is located on an outerside in the radial direction with respect to the tooth-bottom circle 50m. As a result, the through-hole 50 g can be disposed in a portion whichis close to an outer periphery in the radial direction of the drivengear 50 and thus, a length of the foot part 62 h of the turningrestriction part 62 described below can be set longer.

In addition, the protruded shape part 50 n is formed with a relief part50 t on the first direction “R1” side of the lever turning restrictionpart 50 h and a support face 50 u on the first direction “R1” side ofthe relief part 50 t. As shown in FIG. 24, the relief part 50 t isstructured to be recessed to an outer side in the radial direction ofthe driven gear 50 with respect to the lever turning restriction part 50h so as not to contact with the turning shaft 62 a of the turningrestriction part 62 in the protruded shape part 50 n. As a result, asshown in FIG. 24, a gap space 50 v is formed between the turning shaft62 a and the relief part 50 t in a state that the turning restrictionpart 62 is contacted with the lever turning restriction part 50 h. InFIGS. 18 through 21, the gap space 50 v is not shown.

As shown in FIG. 24, in this embodiment, since the gap space 50 v isprovided, the lever turning restriction part 50 h and the turning shaft62 a are set in a separated state from each other and a contact positionof the lever turning restriction part 50 h with the second contact part62 d of the turning restriction part 62 can be set in a separatedposition from the turning shaft 62 a.

For example, in a case that the relief part 50 t is not provided, theturning shaft 62 a and the lever turning restriction part 50 h arecontacted with each other and thus, due to dimensional variation of theturning shaft 62 a in manufacturing, a tip end position of the leverpart 62 b becomes unstable in its turning direction. As a result, acontact position with the protruded part 46 b of the drive gear 46becomes unstable and thus, the position in a power non-transmissionstate in the power transmission switching part 52 becomes unstable. Inthis embodiment, the relief part 50 t forms the gap space 50 v withrespect to the turning shaft 62 a and thus, influence of dimensionalvariation of the turning shaft 62 a in manufacturing can be reduced andthe tip end position of the lever part 62 b can be stabilized.

The support face 50 u is formed so as to be flush with a part of aninner circumferential face of the through-hole 50 g and is extended fromthe through-hole 50 g to an upper part of the protruded shape part 50 nlocated on an upper part of the through-hole 50 g. Therefore, theturning shaft 62 a is supported by the support face 50 u along an axialdirection.

[Turning Restriction Part]

As shown in FIG. 11, the turning restriction part 62 is provided withthe turning shaft 62 a, the lever part 62 b and the foot part 62 h. Thelever part 62 b is provided with a first contact part 62 c, a secondcontact part 62 d and a spring holding part 62 e. The spring holdingpart 62 e is provided with a spring contact part 62 f as an “urgingmember contact part” and a spring coming-off prevention part 62 g.

As shown in FIG. 4, the turning restriction part 62 is turnably attachedin the upper part of the driven gear 50. Specifically, the turning shaft62 a and the foot part 62 h of the turning restriction part 62 areinserted into the through-hole 50 g and the slit part 50 q of the drivengear 50 (FIG. 8). The turning restriction part 62 is structured so thatthe turning shaft 62 a is turnable with respect to the driven gear 50.

The point with the reference sign “C1” (FIG. 24) indicates a turningcenter of the turning shaft 62 a of the turning restriction part 62. Inthis embodiment, the turning restriction part 62 is attached to thedriven gear 50 so that the turning center “C1” of the turning shaft 62 ais located on an inner side in the radial direction of the tooth-bottomcircle 50 m of the driven gear 50.

As shown in FIGS. 11 and 24, in this embodiment, the lever part 62 b isprovided on one end side in the axial direction of the turning shaft 62a, and the foot part 62 h is provided on the other end side. In thisembodiment, the lever part 62 b is formed to be a circular arc-shapedlever which is extended from the turning shaft 62 a. When the turningrestriction part 62 is attached to the driven gear 50, the secondcontact part 62 d of the lever part 62 b is formed on the outer side inthe radial direction with respect to the driven gear 50. In thisembodiment, the second contact part 62 d is structured to be a curvedsurface which is extended along a circumferential direction of thedriven gear 50. A tip end of the lever part 62 b is formed with thefirst contact part 62 c and the spring holding part 62 e.

As shown in FIG. 24, the other end 60 b of the torsion spring 60 iscontacted with a spring contact part 62 f of the spring holding part 62e of the lever part 62 b of the turning restriction part 62, and thelever part 62 b is pressed by the other end 60 b of the torsion spring60. The spring coming-off prevention part 62 g of the spring holdingpart 62 e is provided on an opposite side to the spring contact part 62f with the other end 60 b of the torsion spring 60 interposedtherebetween. The spring coming-off prevention part 62 g prevents theother end 60 b of the torsion spring 60 from coming off from the springholding part 62 e when the other end 60 b of the torsion spring 60contacting with the spring contact part 62 f is separated from thespring contact part 62 f according to a turning state of the turningrestriction part 62. Therefore, the torsion spring 60 can be held with asimple structure.

In this embodiment, the spring contact part 62 f is provided at a tipend of the lever part 62 b. An urging force of the torsion spring 60which urges the spring contact part 62 f applies a turning moment in aclockwise direction in FIG. 24 to the turning restriction part 62. Amagnitude of the turning moment is determined by a distance from thecenter “C1” of the turning shaft 62 a to the spring contact part 62 fand the urging force of the torsion spring 60. In this embodiment, thespring contact part 62 f is provided at a tip end of the lever part 62 band thus, even when an urging force of the torsion spring 60 is small, alarge torque can be obtained. As a result, when the lever part 62 b ofthe turning restriction part 62 is separated from the protruded part 46b, the tip end of the lever part 62 b can be surely returned by theurging force of the torsion spring 60 to a position restricted by thelever turning restriction part 50 h which is a position beforecontacting with the protruded part 46 b.

In this embodiment, the turning restriction part 62 receives an urgingforce of the torsion spring 60 so that the second contact part 62 d ofthe lever part 62 b contacts with the lever turning restriction part 50h of the driven gear 50 to press the lever turning restriction part 50h. In other words, the lever part 62 b of the turning restriction part62 is urged toward an outer side in the radial direction of the drivengear 50 by the urging force of the torsion spring 60, and turning of theturning restriction part 62 to the outer side in the radial direction isrestricted at a position where the second contact part 62 d and thelever turning restriction part 50 h are contacted with each other.

On the other hand, when the second contact part 62 d is pressed towardan inner side in the radial direction of the driven gear 50 against theurging force of the torsion spring 60, the turning restriction part 62is turned toward the inner side in the radial direction of the drivengear 50 with the turning shaft 62 a as a center. When pressing againstthe second contact part 62 d to the inner side in the radial directionis released, the lever part 62 b is turned by the urging force of thetorsion spring 60 and returned to the position where the second contactpart 62 d and the lever turning restriction part 50 h are contacted witheach other.

In FIG. 24, the arrow with the reference sign “F1” indicates a directionin which the torsion spring 60 urges the spring contact part 62 f. Inthis embodiment, the foot part 62 h of the turning restriction part 62is extended from the turning shaft 62 a toward an opposite directionwith respect to the urging direction “F1” by the other end 60 b of thetorsion spring 60. Specifically, the foot part 62 h is extended from theturning shaft 62 a toward an inner side direction in the radialdirection of the driven gear 50. In this embodiment, the oppositedirection to the urging direction “F1” includes, in addition to thedirection where the urging direction “F1” is reversed by 180 degrees, adirection including a vector component to the opposite direction to theurging direction “F1” as a vector component of force.

In FIG. 25, when the torsion spring 60 urges the spring contact part 62f, the turning restriction part 62 is going to turn in a clockwisedirection in FIG. 25 with the center “C2” in an axial direction of theturning shaft 62 a as a center. However, in this embodiment, when theturning restriction part 62 is going to turn in the clockwise direction,the foot part 62 h extended toward an opposite direction to the urgingdirection “F1” is pressed to the foot part accommodation part 50 s tosuppress an inclination of the turning shaft 62 a and restrict turningof the turning restriction part 62. In addition, the support face 50 urestricts the turning of the turning restriction part 62 similarly tothe foot part 62 h and restricts an inclination in the clockwisedirection of the turning shaft 62 a by supporting the turning shaft 62a.

Further, the foot part 62 h is structured so as to extend from theturning shaft 62 a toward an inner side direction in the radialdirection of the driven gear 50 and thus, in comparison with a case thatthe foot part 62 h is extended to an outer side direction in the radialdirection of the driven gear 50, a length of the foot part 62 h can bemade longer. As a result, the turning shaft 62 a can be hard to beinclined.

[Valve Body]

The valve body 56 will be described below with reference to FIGS. 7, 13Aand 13B. As shown in FIGS. 13A and 13B, the valve body 56 is structuredas a disk-shaped member. A through-hole 56 a is provided in a centerpart of the valve body 56. The support shaft 54 is inserted into thethrough-hole 56 a. An under face of the valve body 56 is structured tobe a sliding surface 56 b which slides on the valve seat face 34 c ofthe valve seat constituting member 34. A part of the sliding surface 56b of the valve body 56 is cut out to be structured as a cut-out part 56c.

As shown in FIG. 13B, the cut-out part 56 c is formed in a shape whichis recessed to an upper side with respect to the sliding surface 56 b ofthe valve body 56. Two through-holes 56 d are provided in the cut-outpart 56 c. In this embodiment, as an example, a boss not shown which isprotruded from an under face of the driven gear 50 is inserted into thethrough-hole 56 d, and the driven gear 50 and the valve body 56 arestructured to be turnable in an integral manner.

Further, the valve body 56 is provided with an orifice 56 e which ispenetrated in an upper and lower direction and is opened in the slidingsurface 56 b. In this embodiment, the orifice 56 e has a portion whosewidth is narrower than the first fluid outlet 34 a and the second fluidoutlet 34 b in the path of a fluid. More preferably, the orifice 56 ehas a portion whose width is the narrowest in the path of the fluid.

Main structures of the valve drive device 10 and the valve body drivemechanism 30 have been described. Next, fluid control of the valve body56 by the valve body drive mechanism 30, a power transmission state ofthe drive gear 46 to the driven gear 50, and a power non-transmissionstate will be described below.

[Fluid Control by Valve Body]

Flow rate control of a fluid from the fluid inlet port 28 b to at leastone of the first fluid outlet 34 a and the second fluid outlet 34 b willbe described below with reference to FIGS. 14 through 17. In the step S0in FIG. 15, the drive gear 46 is located at an origin position withrespect to the driven gear 50. A relationship between the teeth of thedrive gear 46 and the teeth of the driven gear 50 at the origin positionwill be described below.

As shown in FIG. 15, in the step S0 (origin position), the cut-out part56 c of the valve body 56 is located above the first fluid outlet 34 aand the second fluid outlet 34 b. Therefore, the valve body 56 is set ina state that the valve body 56 does not close the first fluid outlet 34a and the second fluid outlet 34 b and thus, the first fluid outlet 34 aand the second fluid outlet 34 b are set in an open state. As a result,the fluid supplied from the fluid inlet 28 b to the valve chamber 32 isflowed out to the first outflow pipe 16 and the second outflow pipe 18through the first fluid outlet 34 a and the second fluid outlet 34 b(see opening/closing mode in FIG. 14).

Next, the motor 24 is driven and rotated to rotate the rotor 40 and thedrive gear 46 in the first direction “R1”. In this case, the driven gear50 engaged with the drive gear 46 is turned by the drive gear 46(clockwise direction in FIG. 15) and shifted to a state of the step S1(middle view in FIG. 15). The valve body 56 slides on the valve seatconstituting member 34 in the clockwise direction in FIG. 15 bydriven-turning of the driven gear 50 in a state that the sliding surface56 b is closely contacted with the valve seat face 34 c. Also in thestep S1, the cut-out part 56 c is located above the first fluid outlet34 a and the second fluid outlet 34 b and thus, the first fluid outlet34 a and the second fluid outlet 34 b are set in an open state, in otherwords, an open mode in FIG. 14.

As shown in the bottom view in FIG. 15, when the drive gear 46 isfurther turned in the first direction “R1”, the state of the step S1 isshifted to a state of the step S2. In this state, the orifice 56 e islocated above the first fluid outlet 34 a, and the cut-out part 56 c islocated above the second fluid outlet 34 b. The first fluid outlet 34 ais set in a state that a flow rate of the fluid flowing out from thefirst fluid outlet 34 a is restricted by the orifice 56 e.

In other words, in comparison with the flow rate of the fluid flowingout from the first fluid outlet 34 a in a completely opened state likethe step S0 and the step S1, a flow rate of the fluid flowing out fromthe first fluid outlet 34 a is reduced in a restricted state by theorifice 56 e. In other words, a minute open mode in the step S2 in FIG.14 is obtained. The second fluid outlet 34 b is maintained in the openstate and is an open mode.

Next, as shown in an upper view in FIG. 16, when the drive gear 46 isfurther turned in the first direction “R1”, the state of the step S2 isshifted to a state of the step S3. In this state, the orifice 56 e isdeviated from an upper position of the first fluid outlet 34 a. Thefirst fluid outlet 34 a is covered by the sliding surface 56 b of thevalve body 56 and is closed. Therefore, the first fluid outlet 34 a isset in a closed mode (FIG. 14) and a path of the fluid from the valvechamber 32 to the first outflow pipe 16 is blocked. On the other hand,the cut-out part 56 c is located above the second fluid outlet 34 b.Therefore, the second fluid outlet 34 b is maintained in the open stateand in the open mode (FIG. 14).

Next, as shown in the middle view in FIG. 16, when the drive gear 46 isfurther turned in the first direction “R1”, the state of the step S3 isshifted to a state of the step S4. In this state, the first fluid outlet34 a is covered by the sliding surface 56 b of the valve body 56 and isclosed. Therefore, the first fluid outlet 34 a maintains the state ofthe closed mode (FIG. 14) continuously from the step S3, and maintainsthe state that a path of the fluid from the valve chamber 32 to thefirst outflow pipe 16 is blocked.

In addition, the orifice 56 e is located above the second fluid outlet34 b. Therefore, the second fluid outlet 34 b is set in a state that aflow rate of the fluid flowing out from the second fluid outlet 34 b isrestricted by the orifice 56 e and set in a minute open mode in the stepS4 in FIG. 14.

Next, as shown in the bottom view in FIG. 16, when the drive gear 46 isfurther turned in the first direction “R1”, the state of the step S4 isshifted to a state of the step S5. In the state of the step S5, thefirst fluid outlet 34 a and the second fluid outlet 34 b are covered bythe sliding surface 56 b of the valve body 56 and set in a closed state.In other words, the closed modes in the step S5 in FIG. 14 are obtained.In this state, paths of the fluid from the valve chamber 32 to the firstoutflow pipe 16 and the second outflow pipe 18 are blocked.

Next, as shown in FIG. 17, when the drive gear 46 is further turned inthe first direction “R1”, the state of the step S5 is shifted a state ofthe step S6. In the state of the step S6, the cut-out part 56 c islocated above the first fluid outlet 34 a again. Therefore, the firstfluid outlet 34 a is set in a completely open state and an open mode inFIG. 14 is obtained. On the other hand, the second fluid outlet 34 b iscovered by the sliding surface 56 b of the valve body 56 and maintainsthe closed state and thus, a state that a path of the fluid from thevalve chamber 32 to the second outflow pipe 18 is blocked is maintained.In other words, a closed mode of the step S6 in FIG. 14 is obtained.

In this embodiment, when the valve body 56 is turned with respect to thevalve seat constituting member 34 by the motor 24, each of the firstfluid outlet 34 a and the second fluid outlet 34 b can be switched to anopen state, a minute open state or a closed state and thus, flow ratesof the fluid which are respectively flowed out from the valve chamber 32to the first outflow pipe 16 and the second outflow pipe 18 can beadjusted.

[Switching from Power Transmission State to Power Non-Transmission Statein Power Transmission Switching Part]

With reference to FIGS. 18 and 19, an origin position return operationof the power transmission switching part 52 of the valve body drivemechanism 30 will be described below. In the step S7, the drive gear 46is turned in the second direction “R2”. In the state of the step S7, thegear part 46 a of the drive gear 46 is engaged with the meshing part 50a of the driven gear 50. The step S7 shows a state that, after the drivegear 46 has been rotated in the first direction “R1” to turn the drivengear 50, the rotational direction of the drive gear 46 is switched tothe second direction and becomes a state going to return to the originposition.

When the step S7 is further shifted to the step S8, the drive gear 46 isreturned to the origin position with respect to the driven gear 50. Theorigin position is a state that an engaging state of the gear part 46 aof the drive gear 46 with the meshing part 50 a of the driven gear 50 isreleased and the gear part 46 a is located within the non-meshing part50 b of the driven gear 50. In this state, a power non-transmissionstate is realized that power is not transmitted from the drive gear 46to the driven gear 50 when the drive gear 46 is rotated in the seconddirection.

Specifically, as shown in the views of the step S7 through the step S12,when the drive gear 46 is turned in the second direction “R2”, the fourprotruded parts 46 b are also turned in the second direction “R2”. Asprogressing from the step S7 to the step S9, the protruded part 46 bfacing the second contact part 62 d of the turning restriction part 62comes close to the second contact part 62 d accompanied with turning inthe second direction “R2” and contacts with the second contact part 62 din the step S9.

When the drive gear 46 is further turned in the second direction “R2”,the protruded part 46 b contacted with the second contact part 62 d isalso going to turn in the second direction “R2”. In this case, theprotruded part 46 b presses the second contact part 62 d against theurging force of the torsion spring 60 as shown in the step S10 and thestep S11. As a result, the turning restriction part 62 is turned towardan inner side in the radial direction of the driven gear 50 with theturning shaft 62 a as a center.

After that, as shown in the step S11 and the step S12, when the drivegear 46 is further turned in the second direction “R2”, the protrudedpart 46 b pressing the second contact part 62 d is separated from thesecond contact part 62 d. As a result, the turning restriction part 62is turned toward an outer side in the radial direction by the urgingforce of the torsion spring 60, and is turned to the position where thesecond contact part 62 d is contacted with the lever turning restrictionpart 50 h of the driven gear 50.

In this embodiment, when the drive gear 46 is turned in the seconddirection “R2” in a state that the gear part 46 a of the drive gear 46is located in the non-meshing part 50 b of the driven gear 50, theprotruded parts 46 b repeat intermittently contacting with andseparating from the second contact part 62 d of the turning restrictionpart 62 and the gear part 46 a continues to idle in the non-meshing part50 b. Therefore, a tooth of the drive gear 46 and a tooth of the drivengear 50 can be prevented from carelessly contacting with each other in apower non-transmission state and thus, collision noise generated whengear teeth are collided with each other can be prevented.

When idling of the gear part 46 a is continued within the non-meshingpart 50 b, a released state continues that an engaging state of the gearpart 46 a of the drive gear 46 with the meshing part 50 a of the drivengear 50 is released. As a result, a power non-transmission state inwhich power of the motor 24 is not transmitted from the drive gear 46 tothe driven gear 50 is maintained. Therefore, a possibility that step-outoccurs in the motor 24 can be reduced, and noise caused by step-out canbe suppressed.

[Second Turning Restriction Part]

The second turning restriction part 50 k will be described below withreference to FIGS. 23A and 23B. FIGS. 23A and 23B show a relationshipbetween the drive gear 46 and the driven gear 50 in a state from thestep S10 to the step S11. In FIG. 23A, when the protruded part 46 bcontacts with the second contact part 62 d of the turning restrictionpart 62 and presses the second contact part 62 d, since the protrudedpart 46 b is turned in the second direction “R2”, the second contactpart 62 d is pressed to turn in a counterclockwise direction in FIG.23A.

In this case, the second contact part 62 d pressed by the protruded part46 b is going to turn in the counterclockwise direction in FIGS. 23A and23B together with the driven gear 50. In this embodiment, the drivengear 50 is provided with the second turning restriction part 50 k on thefirst direction “R1” side of the non-meshing part 50 b. When the drivengear 50 is turned in the counterclockwise direction in FIG. 23A togetherwith second contact part 62 d, the second turning restriction part 50 kcontacts with a gear of the gear part 46 a of the drive gear 46 which islocated in the non-meshing part 50 b (FIG. 23A).

When the second turning restriction part 50 k contacts with the tooth ofthe gear part 46 a, turning of the driven gear 50 in thecounterclockwise direction in FIGS. 23A and 23B is restricted. Inaddition, in this state, even when the drive gear 46 continues turningin the second direction “R2”, the second turning restriction part 50 kmaintains a contacted state with either tooth of the gear part 46 a(FIG. 23B) and thus, a turning restriction state of the driven gear 50is maintained. In this manner, the gear part 46 a of the drive gear 46is capable of idling in the non-meshing part 50 b and the powernon-transmission state can be maintained.

[Second Contact Part]

In addition, an advantage that the second contact part 62 d isstructured to be a curved surface will be described below with referenceto FIGS. 26A and 26B. FIG. 26A shows a turning restriction part 66 inwhich the second contact part is formed in a straight shape. A turningrestriction part 66 is provided with a turning shaft 66 a, a lever part66 b and a second contact part 66 c. FIG. 26A shows displacement of aturning state of the turning restriction part 66 having the lever part66 b in a straight shape, and FIG. 26B shows displacement of a turningstate of the turning restriction part 62 in this embodiment.

In FIG. 26A, when the second contact part 66 c in a straight shapecontacts with the protruded part 46 b, the second contact part 66 c isturned to an inner side in a radial direction of the driven gear 50. Theprotruded part 46 b which contacts with the second contact part 66 c isturned in the second direction “R2” along the second contact part 66 cin a straight shape. In this case, the second contact part 66 c having astraight shape becomes in a pushed state to an inner side in the radialdirection of the driven gear 50 until immediately before the secondcontact part 66 c is separated from the protruded part 46 b. When theprotruded part 46 b is separated from the second contact part 66 c, theturning restriction part 66 is turned by a turning amount “W1” by anurging force of a torsion spring 60 not shown to a position where thesecond contact part 66 c is contacted with the lever turning restrictionpart 50 h. The two-dot chain line in FIG. 26A schematically shows thesecond contact part 66 c contacting with the lever turning restrictionpart 50 h and a position of the protruded part 46 b in this state.

On the other hand, in FIG. 26B, when the second contact part 62 dstructured to be a curved surface contacts with the protruded part 46 b,the second contact part 62 d is turned to an inner side in the radialdirection of the driven gear 50. When the drive gear 46 is turned in thesecond direction “R2”, the protruded part 46 b slides and moves on thesecond contact part 62 d. In this case, the second contact part 62 d isformed in a curved surface along a circumferential direction of thedriven gear 50 and thus, accompanied with turning in the seconddirection “R2” of the protruded part 46 b, the second contact part 62 dis gradually returned from the pushed state to the inner side in theradial direction of the driven gear 50 to an outer side in the radialdirection. Then, when the protruded part 46 b is separated from thesecond contact part 62 d, the second contact part 62 d is returned to acontacting position with the lever turning restriction part 50 h by aturning amount “W2”. The two-dot chain line in FIG. 26B schematicallyshows the second contact part 62 d contacting with the lever turningrestriction part 50 h and a position of the protruded part 46 b in thisstate.

In this case, the turning restriction part 62 starts turning toward anouter side in the radial direction from a state before the protrudedpart 46 b is separated from the second contact part 62 d. Therefore, incomparison with the turning amount “W1” of the turning restriction part66, the turning amount “W2” to an outer side in the radial directionwhen the protruded part 46 b is separated from the second contact part62 d can be made small. As a result, an impact when the second contactpart 62 d contacts with the lever turning restriction part 50 h can bereduced and an impact sound (noise) can be suppressed.

[Switching from Power Non-Transmission State to Power TransmissionState]

Next, switching from the power non-transmission state to the powertransmission state will be described below with reference to FIGS. 20and 21. In this embodiment, as shown in the step S13, the drive gear 46is aligned to the origin position in a state that the gear part 46 a ofthe drive gear 46 is located in the non-meshing part 50 b of the drivengear 50, in other words, in the power non-transmission state. Thepositioning of the origin position of the drive gear 46 is performed byexciting the stator 36 in a predetermined excitation pattern.

In the step S14, when the drive gear 46 starts turning in the firstdirection “R1”, the protruded part 46 b contacts with the first contactpart 62 c of the turning restriction part 62 and presses the turningrestriction part 62, i.e., the driven gear 50 to the clockwise directionin FIG. 20. In this embodiment, the protruded part 46 b contacting withthe first contact part 62 c presses the first contact part 62 c towardthe turning shaft 62 a side in a direction intersecting the firstcontact part 62 c and thus, the turning restriction part 62 is unable toturn. As a result, the driven gear 50 is pressed by the protruded part46 b through the first contact part 62 c of the turning restriction part62 and is turned to the clockwise direction in FIG. 20.

As a result, as shown in the step S15, a tooth of the gear part 46 a ofthe drive gear 46 goes out from the non-meshing part 50 b of the drivengear 50 and another tooth of the gear part 46 a starts engagement with atooth of the meshing part 50 a. In this manner, the power transmissionswitching part 52 is switched from the power non-transmission state tothe power transmission state. In addition, when the drive gear 46 isturned in the first direction “R1” side, as shown in the step S16, atooth of the gear part 46 a and a tooth of the meshing part 50 a areengaged with each other and the driven gear 50 continues to turn in theclockwise direction in FIG. 21.

When the drive gear 46 is further turned to the first direction “R1”side, as shown in the step S17, the driven gear 50 can be turned in theclockwise direction in FIG. 21 and the operations of the valve body 56from the step S1 to the step S6 can be performed.

Next, a relationship between the drive gear 46 and the driven gear 50 atthe origin position (state of the step S13 in FIG. 20) will be describedbelow with reference to FIG. 22. In this embodiment, when the drive gear46 is located at the origin position, the protruded part 46 b is locatedat a position facing the first contact part 62 c of the turningrestriction part 62. Further, a lock avoiding tooth 46 c is formed at aposition corresponding to the protruded part 46 b in a circumferentialdirection of the drive gear 46.

In FIG. 22, a circular arc shown by the alternate long and short dashline shows a tooth-tip circle of the teeth other than the lock avoidingtooth 46 c in the gear part 46 a of the drive gear 46. In FIG. 22, in astate that the drive gear 46 is located at the origin position, thetooth 50 j at a boundary between the meshing part 50 a and thenon-meshing part 50 b of the driven gear 50 is located at a positioninterfering with the tooth-tip circle of the teeth other than the lockavoiding tooth 46 c.

In this state, in a case that a tooth other than the lock avoiding tooth46 c is disposed at the position of the lock avoiding tooth 46 c, whenthe drive gear 46 is going to turn in the first direction, the tooth 50j of the driven gear 50 and the tooth other than the lock avoiding tooth46 c disposed at the position of the lock avoiding tooth 46 c may becontacted with each other to cause a lock state of the drive gear 46 andthe driven gear 50.

In this embodiment, when the drive gear 46 is located at the originposition, the lock avoiding tooth 46 c of the drive gear 46 is disposedso as to come close to the tooth 50 j of the driven gear 50. Therefore,the tooth-tip circle of the lock avoiding tooth 46 c is smaller than thetooth-tip circle of the teeth other than the lock avoiding tooth 46 cand thus, a gap space 64 is provided between the tooth 50 j of thedriven gear 50 and the lock avoiding tooth 46 c of the drive gear 46.When the gap space 64 is provided, a lock state of the drive gear 46 andthe driven gear 50 can be avoided. As a result, in the powertransmission switching part 52, switching from the powernon-transmission state to the power transmission state between the drivegear 46 and the driven gear 50 can be smoothly performed and an abnormaloperation (displacement of the position of the gear part 46 a of thedrive gear 46 for an excitation pattern) and occurrence of an operationfailure can be suppressed.

As described above, in this embodiment, the turning restriction part 62in the power transmission switching part 52 is structured so that, in acase that the drive gear 46 is rotated in the first direction, theturning restriction part 62 permits turning of the driven gear 50 and,in a case that the drive gear 46 is rotated in the second direction, theturning restriction part 62 restricts turning of the driven gear 50. Inother words, the turning restriction part 62 is structured as a clutchmechanism. When the turning restriction part 62 in this embodimentutilizes a structure of a known clutch mechanism, a design time and costcan be reduced.

The turning restriction part 62 in this embodiment transmits power fromthe drive gear 46 to the driven gear 50 when the drive gear 46 isrotated in the first direction and, when the drive gear 46 is rotated inthe second direction, power transmission from the drive gear 46 to thedriven gear 50 is disconnected. Therefore, only when a rotationaldirection of the drive gear 46 is switched, a power transmission statecan be switched and a structure of the turning restriction part 62 canbe simplified.

[Foreign Matter Entry Restraining Part] FIGS. 27 Through 31

Next, a specific structure of a foreign matter entry restraining partwill be described in detail below which is provided so that, in a casethat the valve drive device 10 is installed in a fluid path where afluid flowing through an inside of the valve drive device 10 includesforeign matters such as copper powder, a possibility that a foreignmatter enters to a portion (power transmission switching part 52) wherea power transmission switching of the valve body drive mechanism 30 isperformed to cause an operation failure is reduced.

FIGS. 27 and 29 are perspective views showing a valve body drivemechanism 30 provided with a foreign matter entry restraining part inaccordance with an embodiment of the present invention which is viewedfrom an upper side. In this embodiment, the lever part 62 b of theturning restriction part 62 performs a contacting operation with theturning protruded part 46 b of the drive gear 46 and a separatingoperation in which the lever part 62 b is turned against an urging forceof the torsion spring 60 and is separated from a contact position withthe lever turning restriction part 50 h. In this embodiment, a foreignmatter entry restraining part 63 is provided which covers a region 53between the lever part 62 b performing the above-mentioned contactingand separating operation and the lever turning restriction part 50 h.

The region 53 is an area formed by a face of the second contact part 62d of the lever part 62 b and a face of the lever turning restrictionpart 50 h which are faced each other (see also FIGS. 33A and 33Bdescribed below). An opening area of the region 53 becomes large whenthe lever 62 b is turned and separated from the contact position withthe lever turning restriction part 50 h and thus, in a case that foreignmatters such as copper powder are included in the liquid flowing throughthe inside of the valve drive device 10, the foreign matter may beentered into an inside of the region 53.

In this embodiment, as described above, the foreign matter entryrestraining part 63 is provided so as to cover the region 53. Even whenthe valve drive device 10 is installed in a path of a fluid includingforeign matters such as copper powder, the foreign matter is restrainedfrom entering the region 53 by the foreign matter entry restraining part63. As a result, a possibility can be reduced that the lever part 62 bis unable to return to the original contact position with the leverturning restriction part 50 h. Therefore, a possibility that the powertransmission switching part 52 occurs an operation failure due to aforeign matter can be reduced.

An example of a structure of the foreign matter entry restraining part63 in this embodiment will be described below with reference to FIG. 30.The foreign matter entry restraining part 63 is integrally provided withthe lever part 62 b of the turning restriction part 62. Specifically,the foreign matter entry restraining part 63 is projected in an umbrellashape at an upper position of the second contact part 62 d of the leverpart 62 b in FIG. 30 so as to cover the region 53 from an upper side.

As shown in FIG. 28, a rear face 63 b of the foreign matter entryrestraining part 63 faces a top face 51 of the protruded shape part 50 nthrough a clearance “g”. In FIG. 28, the clearance “g” is shown largerin order to easily recognize the clearance in the drawing. However, froma viewpoint of foreign matter entry restraint, it is preferable that theclearance “g” is set to be smaller in an allowable range. In thisexample, the spring holding part 62 e is structured so that the springcoming-off prevention part 62 g shown in FIG. 11 is not provided.

As described above, the foreign matter entry restraining part 63 isprovided in the lever part 62 b and thus, entry of a foreign matter canbe restrained in an easy structure and easy manufacturing.

A size of the foreign matter entry restraining part 63 in thisembodiment will be described below with reference to FIGS. 31A and 31B.In this embodiment, in a state that the lever part 62 b contacts withthe lever turning restriction part 50 h (FIG. 31A), the foreign matterentry restraining part 63 is formed in a shape located on an inner sidein the radial direction of the driven gear 50 with respect to an outerboundary line 83 located at a position corresponding to the leverturning restriction part 50 h (shape so as not to protrude to an outerside in the radial direction). Since other members are normally disposedon an outer side with respect to the outer boundary line 83 of thedriven gear 50, an upper limit of the size of the foreign matter entryrestraining part 63 is determined so as not to interfere with othermembers.

Specifically, in FIG. 31A, most of the top face 51 of the protrudedshape part 50 n is covered by the foreign matter entry restraining part63 from an upper side. FIG. 31B shows a state that the lever part 62 bis pushed by the protruded part 46 b of the drive gear 46 and is turnedagainst the urging force of the torsion spring 60. Even in this turnedstate of the lever part 62 b, the top face 51 is exposed a little.Therefore, a possibility that a foreign matter enters into the region 53is reduced.

In a case that the size of the foreign matter entry restraining part 63is unable to be formed large like FIGS. 31A and 31B, the size may bemade smaller than that in FIGS. 31A and 31B. In this case, it ispreferable that the foreign matter entry restraining part 63 is formedin a shape so as to continuously cover the region 53 at both positions,i.e., the contact position of the lever part 62 b and the positionseparated from the contact position. In other words, even in a case thatthe region 53 is not covered by an excessively projected part like FIGS.31A and 31B, when the foreign matter entry restraining part 63 isprovided with a size capable of covering the region 53 in a state thatthe lever part 62 b is turned and an opening area of the region 53becomes the maximum (FIG. 31B), entry of a foreign matter can berestrained.

As a size of the foreign matter entry restraining part 63, it ispreferable that the size is not less than a size (smallest size)covering the region 53 in a state that the lever part 62 b contacts withthe lever turning restriction part 50 h (FIG. 31A). In other words, in astate that the lever part 62 b is turned and an opening area of theregion 53 becomes the maximum (FIG. 31B), the foreign matter entryrestraining part 63 may be formed in a size that does not cover a partof the region 53. Even in the case of the above-mentioned smallest size,a restraining effect of entry of a foreign matter into the region 53 canbe obtained in comparison with a case that no foreign matter entryrestraining part 63 is provided and thus, in a case that it ispreferable that the foreign matter entry restraining part 63 is formedin a smaller size, the size may be set in the preferable size.

[Another Embodiment of Foreign Matter Entry Restraining Part] FIG. 32

An example of the foreign matter entry restraining part 163 in anotherembodiment will be described below with reference to FIG. 32. In theembodiment shown in FIGS. 27 through 31, the foreign matter entryrestraining part 63 is integrally provided with the lever part 62 b.However, the foreign matter entry restraining part 63 may be providedseparately from the lever part 62 b. In an embodiment shown in FIG. 32,a foreign matter entry restraining part 163 is integrally provided withthe holding member 58. The foreign matter entry restraining part 163 isextended from the flange part 58 a of the holding member 58 to an upperside of the region 53 and covers the region 53 to restrain a foreignmatter from entering.

The above-mentioned foreign matter can be also restrained from enteringinto the region 53 by this foreign matter entry restraining part 163. Asa result, a possibility that the lever part 62 b is unable to bereturned to the original contact position with the lever turningrestriction part 50 h can be reduced.

In this case, the foreign matter entry restraining part 163 is notlimited to the structure provided in the holding member 58 and may beprovided in the lever part 62 b. If possible in space, another dedicatedmember may be used as the foreign matter entry restraining part.

[Interference Avoiding Part] FIGS. 33A Through 35

Next, a specific structure of an interference avoiding part which isprovided so as to reduce a possibility that a foreign matter enters intothe region 53 to cause an operation failure will be described in detailbelow.

FIGS. 33A and 33B are plan views showing a main part of a valve bodydrive mechanism 30 including a turning restriction part 62 provided withan interference avoiding part in accordance with an embodiment of thepresent invention, which are viewed from an upper side.

In this embodiment, FIG. 33A shows a state that the lever part 62 b ofthe turning restriction part 62 contacts with the lever turningrestriction part 50 h of the protruded shape part 50 n and shows a statebefore the lever part 62 b is turned. In other words, FIG. 33A shows astate before the protruded part 46 b of the drive gear 46 turned in thesecond direction “R2” is contacted with the second contact part 62 d ofthe lever part 62 b.

On the other hand, FIG. 33B shows a state that the lever part 62 b isturned and separated from the lever turning restriction part 50 h. Inother words, FIG. 33B shows a state that the protruded part 46 b of thedrive gear 46 turned in the second direction “R2” contacts with thesecond contact part 62 d of the lever part 62 b to push the lever part62 b and thus the lever part 62 b is turned. When the protruded part 46b is further turned in the second direction “R2” from the state shown inFIG. 33B, the protruded part 46 b is separated from the second contactpart 62 d of the lever part 62 b.

In this embodiment, when the drive gear 46 is turned, a locus of acircle (two-dot chain line) formed by tip ends in the radial directionof the protruded parts 46 b is defined as a first circle locus 80. Whenthe protruded part 46 b is turned in the first direction “R1” andcontacts with the first contact part 62 c, a locus of a circle(alternate long and short dash line) formed by a tip end 62 j of thefirst contact part 62 c in the radial direction of the driven gear 50 isdefined as a second circle locus 90.

Further, the second contact part 62 d of the lever part 62 b is formedin a shape having an interference avoiding part 62 k in a portion on thefirst contact part 62 c side in an interference region 85 which issurrounded by a first circle 80 (same reference sign as the first circlelocus is used) formed by the first circle locus 80 and a second circle90 (same reference sign as the second circle locus is used) formed bythe second circle locus 90.

In this embodiment, the above-mentioned interference avoiding part 62 kdescribed as that “the second contact part 62 d is formed in a shapehaving an interference avoiding part 62 k in a portion on the firstcontact part 62 c side in an interference region 85 which is surroundedby a first circle 80 and a second circle 90” means that a retreatingshape for the protruded part 46 b is formed in the second contact part62 d of the lever part 62 b which is to be originally contacted with theprotruded part 46 b and, in the portion of the retreating shape, theprotruded part 46 b does not contact with the lever part 62 b. In otherwords, in the interference region 85, a portion on the first contactpart 62 c side of the second contact part 62 d is formed in a shape soas to have a gap space in which the second contact part 62 d does notcontact with the protruded part 46 b.

According to this embodiment, the lever part 62 b is formed in a shapehaving the interference avoiding part 62 k in the second contact part 62d and thus, a timing when the protruded part 46 b is abutted with thesecond contact part 62 d of the lever part 62 b by turning of the drivegear 46 becomes later than that in a shape having no interferenceavoiding part 62 k. As a result, a time period in a “separated” state ina contacting and separating operation of the lever part 62 b becomesshorter than that in the shape having no interference avoiding part 62k. In the “contacting” state in the above-mentioned operation, a foreignmatter is structurally unable to enter into the region 53 and thus, whena time period of the “separated” state is shortened, a foreign matter ishard to enter into the region 53 by that time.

Therefore, even in a case that the valve drive device 10 is installed ina fluid path including foreign matters such as copper powder, a timeperiod of the “separated” state can be shortened due to the shape havingthe interference avoiding part 62 k and thus, the foreign matter can berestrained from entering into the region 53. Accordingly, a possibilitycan be reduced that the lever part 62 b becomes unable to return to theoriginal contact position. As a result, a possibility that the powertransmission switching part 52 occurs an operation failure due to aforeign matter can be reduced.

An example of the structure of the interference avoiding part 62 k inthis embodiment will be described below with reference to FIGS. 33A and33B. A continuous portion 62 m of the interference avoiding part 62 kfrom a portion of the interference avoiding part 62 k of the secondcontact part 62 d to a portion connected with the tip end 62 j of thefirst contact part 62 c is formed in a curved surface so that theprotruded part 46 b abutting with the interference avoiding part 62 k iscapable of sliding.

When the protruded part 46 b is turned and moved by turning of the drivegear 46 to face a portion corresponding to the interference avoidingpart 62 k of the second contact part 62 d, the protruded part 46 b isinitially in a non-contact state with the second contact part 62 d (FIG.33A). After that, when the protruded part 46 b is moved toward the firstcontact part 62 c side, the non-contact state is switched to a contactstate that the protruded part 46 b is contacted with the second contactpart 62 d. When switched to the contact state, the protruded part 46 bbegins to push the second contact part 62 d through the continuousportion 62 m.

Then, the lever part 62 b is pushed by the turned and moved protrudedpart 46 b and is turned against an urging force with the turning shaft62 a as a support point. As a result, the lever part 62 b is separatedfrom the contact position with the lever turning restriction part 50 h(FIG. 33B).

In this case, in this embodiment, the continuous portion 62 m from theportion corresponding to the interference avoiding part 62 k to theportion connected with the first contact part 62 c is formed in thecurved surface where the protruded part 46 b is capable of sliding andthus, the lever part 46 b can be turned smoothly. Therefore, the turningoperation is stable.

In this case, it is preferable that the slidable curved surface of thecontinuous portion 62 m is a flat face but, when the protruded part 46 bis slidable, the continuous portion 62 m is not limited to a flat face.

A specific structure (shape) of the lever part 62 b provided with theinterference avoiding part 62 k in this embodiment will be describedbelow with reference to FIGS. 33A and 33B.

In this embodiment, a face of a portion of the lever part 62 b whichfaces the lever turning restriction part 50 h is formed to be a curvedsurface so that the entire portion is substantially uniformlysurface-contacted with the lever turning restriction part 50 h to thetip end position 55 in an extending direction of the lever part 62 b.Further, the tip end position 55 of the lever turning restriction part50 h is formed to be a contact position 55 (same reference sign as thetip end position is used) as a base point with respect to the lever part62 b.

The interference avoiding part 62 k is, in this embodiment, structuredto be a recessed part 57 between the contact position 55 of the leverpart 62 b with the lever turning restriction part 50 h and the firstcontact part 62 c.

In this case, the shape of the recessed part 57 is not limited to theshape as shown in FIGS. 33A and 33B, in other words, a substantiallysymmetric shape as a whole which has a shape formed by an inclined facegradually going down from the tip end position 55 toward the continuousportion 62 m. For example, a shape of the recessed part 57 may be formedso as to be retreated in the radial direction of the driven gear 50 fromthe tip end position 55 and then changes the direction by substantiallya right angle to be connected with the continuous portion 62 m.

According to this embodiment, the interference avoiding part 62 k isstructured of the recessed part 57 and thus, a delay of the timing canbe easily realized by the recessed part 57 in a state that the contactstate and the contact position of the lever part 62 b with the leverturning restriction part 50 h are stabilized.

Next, relationships between a turning angle of the drive gear 46, inother words, a turning position of the protruded part 46 b and a turnedposition of the lever part 62 b will be described below by comparing acase that the lever part 62 b does not have the interference avoidingpart 62 k (view on an upper side in FIG. 34 and a graph by the brokenchain line in FIG. 35) with a case that the lever part 62 b has theinterference avoiding part 62 k (view on a lower side in FIG. 34 and agraph by the solid line in FIG. 35) with reference to FIGS. 34 and 35.

In FIG. 34, the operation advances from the first (1) (indicated with acircle) at the left end toward the eighth (8) at the right end throughthe steps 1 through 8. The protruded part 46 b contacts with the secondcontact part 62 d of the lever part 62 b at respective timings to pushand turn the second contact part 62 d and then, the protruded part 46 bis separated from the contact state with the second contact part 62 d ofthe lever part 62 b after passing a state that the turning angle is themaximum turning state to reach the first contact part 62 c side.

As shown in FIGS. 34 and 35, in both cases, both of the protruded parts46 b are in non-contact states with the lever parts 62 at the originposition in the step 1.

In the lever part 62 b having no interference avoiding part 62 k, asshown in the view on the upper side in FIG. 34, the turning protrudedpart 46 b contacts with the lever part 62 b immediately after the step 1to turn the lever part 62 b against the urging force. Therefore, sincethe opening area of the region 53 becomes larger immediately after thestep 1, a foreign matter may easily enter. A time period that theopening area of the region 53 becomes large is in a range from the step1 to the step 7.

On the other hand, in the lever part 6 b provided with the interferenceavoiding part 62 k, as shown in the view on the lower side in FIG. 34,the protruded part 46 b does not contact with the lever part 62 b fromthe step 1 to immediately before the step 3 because the interferenceavoiding part 61 k is provided. The protruded part 46 b contacts withthe lever part 62 b at the position of the step 3 and, after that, theprotruded part 46 b turns the lever part 62 b.

As a result, the opening area of the region 53 becomes large, but thetime period that the opening area of the region 53 becomes large is in arange from the step 3 to the step 7.

Therefore, in the lever part 62 b provided with the interferenceavoiding part 62 k, a time period that a foreign matter may easily enterinto the region 53 is shortened by a range from the step 1 to the step3.

FIG. 35 is a graph showing that, in the lever part 62 k provided withthe interference avoiding part 62 k, a time period that a foreign mattermay easily enter into the region 53 is shortened by a range from thestep 1 to the step 3. As shown in the graph, according to thisembodiment, a time period of the “separated” state is shortened due tothe shape provided with the interference avoiding part 62 k and thus,entering of a foreign matter into the region 53 can be restrained.

Further, in this embodiment, as shown by the solid line (with theinterference avoiding part 62 k) of the graph in FIG. 35, it isstructured that, when the drive gear 50 is turned in the seconddirection “R2” and the protruded part 46 b pushes the second contactpart 62 d of the lever part 62 b, the lever part 62 b is turned with theturning shaft 62 a as a turning support point and a turning angle of thelever part 62 b when the protruded part 46 b is separated from thesecond contact part 62 d becomes the maximum value.

In this embodiment, it is structured that a turning angle of the leverpart 62 b when the protruded part 46 b is separated from the secondcontact part 62 d becomes the maximum value and thus, the lever part 62b is not required to be unnecessarily turned larger as in the case ofthe turning angle of the lever part 62 b having no interference avoidingpart 62 k (graph of the broken line (without the interference avoidingpart 62 k) in FIG. 35). As a result, the structure can be simplified.

Further, in this embodiment, the motor 24 is a stepping motor. Inaddition, this embodiment is structured so that the protruded part 46 bis separated from the second contact part 62 d in a step next to thestep corresponding to the maximum value of the turning angle of thelever part 62 b.

According to this structure, the protruded part 46 b is separated fromthe second contact part 62 d in the step next to the step correspondingto the maximum value of the turning angle of the lever part 62 b andthus, design and operation control can be simplified.

[Foreign Matter Entry Restraining Part and Interference Avoiding Part]FIG. 29, FIGS. 31A and 31B, and the View on the Lower Side in FIG. 34

As shown in FIG. 29, FIGS. 31A and 31B, and the view on the lower sidein FIG. 34, in this embodiment, the lever part 62 b is provided withboth of the foreign matter entry restraining part 63 and theinterference avoiding part 62 k. As shown in FIGS. 31A and 31B, in bothof a state that the lever part 62 b is in a non-contact state with theprotruded part 46 b and before being turned (FIG. 31A), and a state thatthe lever part 62 b contacts with the protruded part 46 b and is turnedto the maximum angle (FIG. 31B), the region 53 is largely covered by theforeign matter entry restraining part 63.

Therefore, entering of a foreign matter into the region 53 can befurther restrained by providing with the foreign matter entryrestraining part 63 and the shape having the interference avoiding part62 k. Accordingly, a possibility that the power transmission switchingpart 52 occurs an operation failure due to a foreign matter can befurther reduced.

In addition, in this embodiment, as shown in FIG. 29, FIGS. 31A and 31B,and the view on the lower side in FIG. 34, the interference avoidingpart 62 k is structured of the recessed part 57 as described above. Theinterference avoiding part 62 k is structured of the recessed part 57 asdescribed above and thus, the effects based on the structure of therecessed part can be obtained in the structure provided with the foreignmatter entry restraining part 63 and the interference avoiding part 62k.

MODIFIED EMBODIMENTS

(1) In the present specification, as described at the beginning, inorder to easily understand the description, the specific structure ofthe foreign matter entry restraining part and the interference avoidingpart is described later and, first, the general structure of the valvedrive device has been described which is capable of reducing noise whenthe valve body is driven and of performing smooth power transmissionswitching with reference to FIGS. 1 through 26B. Then, the structuresincluding the foreign matter entry restraining part 63, the interferenceavoiding part 62 k and both the structures 63 and 62 k have beendescribed with reference to FIGS. 27 through 35.

In the feature structures of the respective embodiments of the presentinvention, the structures described and explained in FIGS. 1 through 26Bare similarly structured in the embodiments in FIGS. 27 through 35 andthus, their descriptions are omitted.

For example, in a case that the region 53 is structured to have the gapspace 50 v described in FIG. 24, there is a possibility that a foreignmatter may enter into the gap space 50 v even when the lever part 62 bis set in a contact state that the lever part 62 b is pressed againstthe lever turning restriction part 50 h by the urging force. When thepresent invention is applied to the region 53 having this structure, theeffect can be largely obtained.

(2) In the embodiment described above, as an example of the “urgingmember”, the turning restriction part 62 is urged by the torsion spring60. However, instead of this structure, the urging member may bestructured of a flat spring.

(3) In this embodiment described above, in the power transmissionswitching part 52, power transmission is structured to be switched byswitching the engagement states (contacting with the first contact part62 c or the second contact part 62 d) of the protruded part 46 b withthe turning restriction part 62. However, instead of the structure, itmay be structured that a known ratchet mechanism is provided in theturning restriction part 62 to idle the drive gear 46.

(4) In the embodiment described above, the foot part accommodation part50 s is structured to provide in the under face 50 r of the driven gear50 to accommodate the foot part 62 h. However, instead of the structure,without providing the foot part accommodation part 50 s in the underface 50 r, it may be structured that a foot part 62 h is protruded fromthe under face 50 r and is turnably disposed so as to contact with theunder face 50 r.

(5) In the embodiment described above, the foot part 62 h is structuredas a single foot part which is extended in a direction opposite to theurging direction of the torsion spring 60. However, instead of thisstructure, it may be structured that a plurality of foot parts isprovided and, for example, a foot part extended in an urging directionof the torsion spring 60 may be provided.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims, rather than theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. A valve drive device comprising a valve body drive mechanism structured to drive a valve body; wherein the valve body drive mechanism comprising: a drive gear structured to be rotatably driven by a motor; a driven gear structured to turn the valve body through rotation of the drive gear in a state that the driven gear is engaged with the drive gear; and a power transmission switching part which is capable of switching between a power transmission state that the drive gear is engaged with the driven gear to transmit power of the motor to the driven gear and a power non-transmission state that an engaging state of the drive gear with the driven gear is released; wherein the power transmission switching part comprises: at least one protruded part which is formed in the drive gear and is protruded in a radial direction of the drive gear; and a turning restriction part which is turnably attached to the driven gear and is engageable with the protruded part; wherein the turning restriction part comprises: a turning shaft which is inserted into the driven gear; and a lever part which is extended from the turning shaft in a circumferential direction of the driven gear and is urged with an urging force toward an outer side in a radial direction of the driven gear; wherein the driven gear comprises a lever turning restriction part structured to contact with the lever part to restrict turning of the turning restriction part to the outer side in the radial direction of the driven gear; wherein the lever part is structured to perform a contact operation with the protruded part being turned and a separating operation from a contact position with the lever turning restriction part against the urging force; wherein the lever part comprises: a first contact part structured to contact with the protruded part when the drive gear is turned to a first direction; and a second contact part structured to contact with the protruded part when the drive gear is turned to a second direction which is an opposite direction to the first direction; wherein when the protruded part is turned to the first direction and is contacted with the first contact part, the lever part is pressed by the protruded part to turn the driven gear, and a tooth of the drive gear and a tooth of the driven gear are engaged with each other and thereby the power transmission state is obtained; wherein when the protruded part is turned to the second direction and is contacted with the second contact part, the lever part is turned to an inner side in the radial direction against the urging force and a tooth of the drive gear is not engaged with a tooth of the driven gear to idle the drive gear and thereby the power non-transmission state is obtained; and wherein in a case that a locus of a circle formed by a tip end in the radial direction of the protruded part when the drive gear is turned is defined as a first circle locus, and that a locus of a circle formed by a tip end of the first contact part in the radial direction of the driven gear when the protruded part is turned to the first direction and is contacted with the first contact part is defined as a second circle locus, the second contact part is formed in a shape which comprises an interference avoiding part on a side of the first contact part in an interference region surrounded by a first circle formed by the first circle locus and a second circle formed by the second circle locus.
 2. The valve drive device according to claim 1, wherein a continuous portion continuing from a portion of the interference avoiding part of the second contact part to the first contact part is formed to be a curved surface on which the protruded part is capable of sliding.
 3. The valve drive device according to claim 1, wherein the interference avoiding part is structured of a recessed part between a contact position of the lever part with the lever turning restriction part and the first contact part.
 4. The valve drive device according to claim 1, wherein when the protruded part pushes the second contact part of the lever part while the drive gear is turned to the second direction, the lever part is turned with the turning shaft as a turning support point, and a turning angle of the lever part when the protruded part is separated from the second contact part is a maximum value.
 5. The valve drive device according to claim 4, wherein the motor is a stepping motor, and the protruded part is separated from the second contact part in a step next to a step corresponding the maximum value of the turning angle of the lever part.
 6. The valve drive device according to claim 1, wherein in a state that the lever turning restriction part restricts turning of the turning restriction part, the lever turning restriction part is formed with a gap space between the lever turning restriction part and the turning shaft.
 7. The valve drive device according to claim 1, wherein the second contact part of the lever part is located on an outer peripheral side in the radial direction of the driven gear and is formed to be a curved surface which is extended along a circumferential direction of the driven gear.
 8. The valve drive device according to claim 1, wherein the driven gear is formed with a protruded shape part which is protruded to an outer side in the radial direction and is protruded from a face on one side of the driven gear in an axial direction of the driven gear, and an inner side in the protruded shape part in the radial direction of the driven gear is formed with the lever turning restriction part.
 9. The valve drive device according to claim 6, wherein when the protruded part contacts with the second contact part and the lever part is turned to an inner side in the radial direction against the urging force, the driven gear comprises a co-turning prevention part which restricts that, when the second contact part is pushed by the protruded part in a turning direction of the protruded part, the driven gear is turned in a direction corresponding to a turning direction of the drive gear.
 10. The valve drive device according to claim 1, wherein the turning restriction part comprises a foot part provided on an opposite side to the lever part of the turning shaft in an axial direction of the turning shaft, and the foot part restricts an inclination of the turning shaft by the urging force which urges the lever part.
 11. The valve drive device according to claim 10, wherein the foot part is extended to an opposite direction to a direction that the lever part is urged.
 12. The valve drive device according to claim 10, wherein the foot part is extended from the turning shaft toward an inner side in the radial direction of the driven gear. 